b'2 



CRAIGEND. . peculiar appearance of ulceration which the fish presented agrees with what he 

 has himself noticed, with the exception that some of the earlier ulcers showed no 

 appearance of fungus to the naked eye. Did not examine them with a micro- 

 scope. As matter of fact, in]the case of fungus destroying an ovum, the fungus 

 does not germinate on a healthy egg in the first instance. When an egg dies 

 and turns white in from 12 houi's to six days according to the temperature 

 (from 33° to 50°) byssus appears on the shell, after some time its hair-like 

 threads involve a neighbouring ovum, on which next day a small round white 

 spot will appear, showing that the spores have pierced the shell and admitted 

 water. A new crop of byssus springs from this spot, and in time involves the 

 next ovum, killing it in like manner, till at last a dozen eggs are entangled in 

 a white mat ; but in no case will byssus germinate on a healthy egg unless its 

 roots are already feeding on a dead one, and even then it is possible that it 

 first kills by the mechanical penetration of its spore admitting water. In this 

 respect byssus differs from algse. 



Very young fry are much subject to fungus ; but jumping against screens 

 and nibbling at each other are generally the prime causes. 



Does not agree with that part of the letter which considers the disease a 

 provision of nature to drive the fish to the salt water. It seems unsupported 

 by sufficient evidence. 



Thinks the disease probably'exists every autumn and spring, and that circum- 

 stances not yet understood determine its extent and virulence. Now that 

 public attention has been drawn to tie subject many cases may be heard cf 

 which would formerly have passed unnoticed. Care must be taken that this 

 is not taken as a proof of increase in the prevalence of the disease. 



Will expose a diseased fish to a current of fresh water and note the effect, 

 and will again make experiments with salt water, and will dissect the next fish 

 that dies and carefully inspect its internal organs, and report results. 



Craigend, Stirling, Thursday, March. 18th, 1880. 



Present : 

 Archibald Young and Spencer Walpole, Esquires. 



Sir James Gibson Maitland, Baronet, Craigend, Stirling. — Has given 

 special attention to the disease since 4th October last. Has noticed fungus 

 on male fish shortly after their milt was ripe. Up to the middle of December 

 found the disease entirely confined to males (last case observed was in March). 

 In every case of male fish dying of disease, the duct leading from the milt sac 

 contained a whitish liquid, which ran freely on* the fish being held up by 

 the gills. A discoloured spot was frequently present between the pectoral 

 fins, varying from the size of a sixpence to that of half-a-crown, and slightly 

 indurated to the touch. This spot and the liquid in the milt duct seemed 

 to be the earliest symptoms of the disease, the ulceration of the mouth 

 appearing from the 4th to the 10th day. The fungus usually appeared in 

 spots about the fourth day. 



Thinks the male fish might die before the fungus appeared. Thinks that a 

 common origin of the disease is in the fact of the males, from some cause, not 

 being able to shed their milt so rapidly as it has ripened in the milt sac ; the 

 glands become relaxed, and the re-absorption of milt so often noticed by pisi- 

 culturists does not take place ; some of the zoosperms probably die in the duct 

 (the very slightest penetration of the water is sufficient to cause this), and set 

 up an irritation, &c. 



Anything tending to increase the disproportion of males to females on the 

 spawning ground would probably increase the number of victims to the 

 disease. Has known hen fish die egg-bound with and without the appearance 

 of fungus. Thinks fungus is always present in water, and readily attacks fish 

 so diseased. 



Thinks Saprolegnia ferax is probably dangerous in two forms, the vegetable 

 cell rooting only in favourable soil, and the microscopic seeds shed by the 



